Even the most fiery chili pepper gets all the heat from no more than 0.1 percent of the fruit. The burning taste comes from a chemical called capsicin, of which only a trace is needed to cause an unwary diner to grab for water.
Chillies are the berries of a species of the potato family, Capsicum Annum. The species include both the small hot types such as the red Tabasco pepper, and the large red and green sweet peppers. Hot peppers dried and crushed yield Cayenne Pepper. Sweet Peppers are used to make Paprika.
The species is native to the Americas, but the largest crops by far are now grown in India.